1. Field of the Invention
The invention concerns a device for reading sheet material.
2. Prior Art
Such a device is known from U.S. Pat. No. 3,980,294. It consists of an endless, perforated belt guided over two rollers. Between the upper and lower section of the belt there is a low-pressure chamber. Above the upper section of the belt there is a light source. This light source has a slit. A paper to be copied is held against this belt by low pressure acting at the perforations of the belt, and in this way the paper is carried past the light source, where the markings of the sheet are detected through the slit. With this known device, markings can be detected that are located on the top side of the sheet. In contrast, markings on the bottom side of the sheet cannot be detected.
A device for electronic transmission of information in text form on paper sheets or reels of paper is known from DE 198 07 944 A1, wherein the paper is transported between transport rollers and opposing counter rollers driven to rotate. In order to detect information on both sides of the paper in a passage, there is a device for detecting information on each side of the paper, where the information is converted into electronic signals in a control unit and then transmitted to a receiver.
The problem dealt with by the invention is the design of a device according to this class so that markings on both the top side of the material and also on the bottom side can be detected.
This problem is solved with the features of the invention by the provision of a device for reading sheet material, consisting of an endless, perforated belt guided over two rollers, of which one is driven, where material is guided from a feeding device to an inlet and the belt transports the material to an outlet, wherein the material is held against the belt by a low pressure acting at the perforations of the belt and there is at least one reading device that detects markings of the material transported by the belt, characterized in that there is an inlet on both sides of one of the rollers, in that the device can be adjusted relative to the feeding device, and in one position, one inlet is located at the height of the feeding device, and in the other position, the other inlet is located at the height of the feeding device, in that for a change from one position to the other, the direction of rotation of the driven rollers is reversed, and in that the one or more reading devices are directed towards the corresponding section of the belt, whose inlet is located at the height of the feeding device.
The device may be further characterized in that each section of the belt is covered by a transparent plate or characterized in that the plates can be removed. Further, the device may be characterized in that there is a low-pressure chamber between the first and the other section or characterized in that between the first and the other section there is at least one fan, whose direction of rotation is reversible, and in that the suction side of the fan is directed towards the corresponding section, whose inlet is located at the height of the feeding device.
The device may be characterized in that the transparent plates are reduced at the inlets or characterized in that the feeding device consists of two transport rollers arranged at a distance from each other with corresponding counter rollers. Further, the driven roller is driven by an electric motor that can change its direction of rotation. Also, the driven roller can be driven by a toothed belt that engages one side of the roller in one position and engages the other side of the roller in the other position. In addition, the reading device can be adjusted in the direction of a section and perpendicular to this direction.
The device may be characterized in that in the region of an outlet there is a detector that detects the leading edges of the material and that generates a signal reducing the speed of the belt when the leading edge is detected. In the device, the periphery of the rollers has pins that engage the perforations of the belt.
The invention relates to a device for the reading of flat material, comprising an endless perforated belt, guided over two rollers, of which one is driven. The material is brought from a feeder device to an inlet and the belt transports said material to an outlet, whereby the material is retained against the belt by a vacuum acting on the perforations of the belt and at least one reading device is provided, for reading the markings from the material being transported on the belt. In conventional devices of this type only markings may be read which lie on the upper surface of the sheet. The aim of the invention is to provide an embodiment of the device with which markings may also be read which lie on the under surface of the sheet. Said aim is achieved, whereby an inlet is arranged on both sides of the rollers, said device is adjustable relative to the feed unit and, in the one position, the one inlet, is at the level of the feed unit and, in the other position, the other inlet is at the level of the feed unit. On an adjustment from the one position to the other a reversal in the direction of rotation of the driven roller occurs and the at least one reading device faces that side of the belt, the inlet of which is at the level of the feed unit.
In addition to the advantage of two-sided readability, another advantage is that there is no restriction on the reading area. Reading is possible both while moving and at a standstill. Due to the small masses to be moved, high acceleration is possible for the sheet material to be transported.